692 



SCIENCE 



[N. S. Vol. XXX. No. 776 



I have accomplished the same result in several 

 cases in subsequent cultures of these forms.- 

 But I find from this summer's cultures that 

 this type differs constantly from the 0. lata 

 of de "Vries, as the latter appears in cultures 

 or as a mutant from 0. Lamarchiana. In bud 

 characters it resembles 0. semilata, but the 

 leaf characters are closer to those of lata than 

 to semilata. Hence while agreeing with the 

 lata mutant in most of its characters, it differs 

 constantly from the lata which is a derivative 

 of the Amsterdam cultures, in its ability to 

 produce a considerable amount of viable pol- 

 len, as well as in the (probably correlated) 

 shape of its buds. 



The frequent association in various genera, 

 of apogamous conditions with the failure to 

 produce pollen, led me to consider the possi- 

 bility that 0. lata might show a similar con- 

 dition. This surmise has since been strength- 

 ened by certain facts recorded by Miss Lutz.^ 

 She found certain 0. lata plants having the 

 lata number of chromosomes, in the first gen- 

 eration of hybrids from 0. lata X 0. gigas. 

 I have referred to this in a recent publication' 

 and suggested that the most probable explana- 

 tion is that they originated apogamously. The 

 facts are these. In a total of about forty 

 plants from the Yi of 0. lata X 0. gigas 

 Miss Lutz found (I.) two plants which were 

 identical with 0. lata in every respect and 

 had fifteen chromosomes ; (II.) six plants which 

 were very similar to 0. gigas, having about 

 thirty chromosomes so far as counts were 

 made ; and (III.) thirty-two plants which, 

 though not clearly characterized in the descrip- 

 tion, seem to have been in part intermediate 

 between 0. lata and 0. gigas, and in part 

 intermediate between 0. Lamarchiana and 0. 

 gigas. A portion of these latter plants are 

 stated to have twenty-two somatic chromo- 

 somes, " others twenty-three and some possibly 



- " Notes on the First Generation Hybrid of 

 CEnothera lata X 0. gigas," Science, 29 : 263-267, 

 1909. 



' " The Behavior of the Chromosomes in Gino- 

 thera lata X 0. gigas," Bot. Gaz., 48; 179-199, 

 pis. 12-14, 1909. This paper deals with the chro- 

 mosome behavior in the germ cells of hybrids 

 having 20 and 21 chromosomes. 



twenty-one chromosomes." Whether these 

 hybrids all had the same individual 0. lata 

 plant as mother is not stated, but if this was 

 the case and the mother had fifteen chromo- 

 somes, then we might expect the two lata 

 plants in the offspring both to have fifteen 

 chromosomes, and the hybrids of class III. 

 to have twenty-one or twenty-two chromosomes 

 (14-1-7 or 14 -(-8), while in the case of the 

 0. gigas-\x\B. plants which are stated to have 

 had thirty chromosomes in the individuals in 

 which a count was made, the expectation 

 would perhaps be twenty-nine (15-|-14). 



How the 0. gigas-Vike individuals having 

 about thirty chromosomes originated must, 

 however, be a matter of conjecture at the 

 present time. 



Miss Lutz calls the 0. lata plants in this 

 cross " extracted latas," which would indicate 

 their hybrid origin. But in view of the fact 

 that they have the lata number of chromo- 

 somes (14 or 15) and in view also of the sub- 

 sequent data which I am about to state, it 

 seems highly probable that they originated 

 apogamously from the 0. lata parent. 



De Vries' made the cross 0. lata X 0. gigas 

 in 1905 and grew one hundred and thirty-three 

 of the oiispring in 1907 and a smaller number 

 in 1908. Of the former number sixty-eight 

 were found to be intermediate between 0. lata 

 and 0. gigas, and sixty-five intermediate be- 

 tween 0. Lamarchiana and 0. gigas, and the 

 1908 culture repeated the same two types, also 

 in about equal proportions. From this it 

 appears that there were no pure 0. lata indi- 

 viduals and hence could have been no apogamy 

 in these cultures at Amsterdam. 



The peculiarities of 0. lata are such that 

 there need be no difficulty in distinguishing 

 it from 0. Lamarchiana or 0. gigas or even 

 from forms intermediate between 0. lata and 

 0. gigas. The further fact that Miss Lutz 

 found the two lata individuals in her cross to 

 have fifteen chromosomes, supports the belief 

 in their apogamous origin. 



In my experiments this summer, to deter- 

 mine more definitely the occurrence of apog- 

 amy in 0. lata, I removed the anthers (which 



* " Bastarde von (Bnothera gigas," Ber. Deutsch. 

 Bot. Gesells., 26a: 754-702, 1908. 



